De systemate orbis cometici, deque admirandis coeli characteribus (transl.
[1][2] The first part of his work (De systemate orbis cometici) followed Galileo's ideas on comets.
[1][2] The second part (De admirandis coeli characteribus) consisted of four main sections.
[1][2] The second part is a list of 40 nebulae, of which roughly 25 have been identified as known objects, the others having too unclear a description for a modern identification.
[1] The third section is an attempt at a unifying theory of celestial objects, and the fourth concerns Copernican heliocentrism.